Not defined messages are usage messages that indicate a variable is used somewhere, but no equation has been defined for it.
This condition does not usually occur when you are working with the Sketch Editor since inputs are defined as you enter the equations for them.
Variables that are not defined are assumed exogenous and must therefore be entered as data for a simulation to proceed. This is designed as a convenience to allow you to cut and paste sectors of a model without having to rewrite input equations. Thus, if the NOT DEFINED messages you get are all expected, you can proceed without difficulty. If not, you need to correct the problem either by adding in the variable that is not defined or correcting spelling inconsistencies.
A common source of NOT DEFINED messages is variable name misspellings. For example suppose you get the two messages:
USE FLAG: "profit" is not used in the model.
NOT DEFINED: "profits" not defined - assumed exogenous.
You have used profit in some places and profits in others for the same concept. In this case, you should correct the spelling to be consistent. Such paired messages as those above are not always on contiguous lines, and you will not receive the USE FLAG message if you have used profit elsewhere already.
